By Ryan Dean
St. Louis (KSDK) -- For the past seven years, the National Park Service has been investigating stains visible on the Gateway Arch.
Since 2005, the parks service says it has spent $731,000 on three studies and it's estimated an additional $200,000 is needed so inspectors can get a closer look at the outside of the Arch near the top.
That means, before the Arch is cleaned (which is recommended to remove the stains) the park service will have spent nearly a million dollars just on studies.
"One of the reasons it takes so long is it's not easy to access to look at closely, nor do we have an operations manual that says 'here's what you do when it starts to get dirty and how to clean it'... We're taking it step by step, we want to do it correctly, we don't want to cause any harm, we don't want to waste dollars starting a process that's incorrect," said Gateway Arch Public Information Officer, Ann Honious.
There is no timetable on when the Arch is slated to be cleaned and it's not known how much the cleaning will cost. The park service stresses the staining is superficial and has not harmed the Arch's structural integrity.